Volcano Report: Facts, Definitions and Details

Volcanoes

1A volcano is an opening in Earth's surface where melted rock, gas and ash can escape. Many volcanoes look like tall mountains shaped like cones. Others are low and wide, and some are hidden deep under the ocean.

2In some places deep under the ground, it is hot enough to melt rock. Melted rock under the ground is called magma. When magma, gas and ash burst out of a volcano, it is called an eruption. Once the melted rock reaches the surface, it has a new name: lava.

3Lava is so hot that it can glow red or orange. Some lava flows slowly downhill like thick syrup. As lava cools, it hardens into solid rock. During some eruptions, a volcano also blasts out ash. Volcanic ash is made of tiny bits of rock, and wind can carry it for miles.

4Many volcanoes have a crater. A crater is a bowl-shaped hole at the top of a volcano. Over many years, layers of cooled lava and ash can pile up around the opening, and the volcano grows taller.

5People often sort volcanoes into three groups. An active volcano has erupted in recent times and could erupt again soon. A dormant volcano has been quiet for a very long time, but it could wake up one day. An extinct volcano is not expected to ever erupt again.

6Volcanoes can be dangerous, but they can also be helpful. Over time, ash and lava rock break down into rich soil that is good for growing plants. Volcanoes have even built new land. The Hawaiian Islands were formed by volcanoes.